friday 1-25 ps intro to earth science earth science? geology meteorology oceanography hydrology...
TRANSCRIPT
Friday 1-25 ps
Intro to earth Science
Earth Science?
• Geology
• Meteorology
• Oceanography
• Hydrology
• Seismology
• Ecology
Definitions
• Earth Science is the study of the earth, how it functions and the connections to the life that lives or has lived on it
• Meteorology – atmosphere
• Oceanography/Hydrology- water
• Seismology- inside the earth
• Ecology- relationship between life and its environment
Our focus
• Overview of the science
• Connection to physical concepts
• History of the Earth
Statistics about the Earth
• Shape of Earth is an oblate spheroid
(only just 40 miles difference in circumferences)
Circumference is about 24,000 miles around
Radius is about 3800 miles
Diameter 7600 miles
Distance between New York and Los Angeles is 2400 miles
• Trip = 1/10 around the world
= 2/3 to the center of the earth
Earth facts
• Relatively smooth for the scale
• Highest mountains are 5.5 miles from sea level
• Deepest trenches about 7 miles below sea level
Facts of Earth
71 % of Earth is covered by water
97% of that water is salty
Air we breathe at this point in earth’s history is made up of
78% nitrogen21 % oxygen1% other gases (including CD)
The Pacific ocean
Largest ocean
at present
64 million square
Miles
It would take 244
States of Texas
To cover the same
area
Trash in the ocean
How old is the Earth?
a) About 7000 years
b) About 4.5 million years
c) About 180 million years
d) About 1.8 billion years
e) About 4.5 billion years
Explanation
A) age derived from calculations based on info from the Bible
B) Age of the first species that could be considered human
C) Last time that Africa was attached to North America
D) First time that multicellular life emerged
E) Time of the formation of Earth
How many lifetimes could a normal modern American have lived since the formation of the
Earth?
About 60 million lifetimes
Change is the only constant in the history of Earth
65 million years ago, the ancestor of the modern whale walked the Earth looking more like a dog than a whale
How hot is the Earth?
• Up to 140° F • Down to -100°F
Black Smoker Vent at the bottom of the ocean (500°F)
Inside the earth?
• Deepest that man has traveled into the earth?
A couple of miles down in the gold mines of South Africa 1 degree for every 33 m
Without air conditioning it would be around 160-170°F
With air conditioning it is 100 degrees with a 100% humidity
South African Gold Miner
Deeper into the earth
• About 20-40 km down = 350 ° F,
the temperature you bake a cake
About 1000-1200 miles down = 2300 ° F
At the center of the Earth = up to 11,000 °F
In other words, 110 times more hot than the hottest summer day you have ever experienced
Scale is different in this portion of the class than before
• Cross section of the earthInner coreOuter CoreMantle
AsthenosphereLithosphere
CrustHydrosphereAtmosphere
Magnetosphere
Inner Core
• Solid Metal, nickel and iron
• Under incredible temp and pressure
• Pressure keeps it solid
• Around 1000 mile thick in diameter
Outer core
• Same composition as the inner core• Less heat and pressure• Liquid• The movement of the Iron liquid, generates the
Earth’s magnetic field• Slightly thicker than inner core
The volume occupied by both cores is about 29.5% of the Earth’s total
Mantle
• Thickest section of the interior of the earth
• The entire mantle Comprises 80% of Earth volume
• The top of the mantle is further divided into 2 important subsections– Lithosphere– Asthenosphere
Mantle subsections
Lithosphere
topmost layer of mantle (nearest to surface of Earth)
solid, brittle
Asthenosphere
underlies the lithosphere
texture like silly-putty, bends under pressure
Crust
• The layer of the earth next to the surface• Very thin
– Oceanic 2-4 miles– Continental 40-65 miles
• The least dense of all layers– Ocean crust is denser than continental crust
• We have never drilled all the way through the crust
The Moho
• The boundary between the crust and the lithosphere
How do you think we know anything about the inside the
earth?
Different form of Echolocation
• Using seismic waves• Created by vibrations of the Earth• Using time to indicate distance and type of
material
• Causes of vibration• Natural: Earthquakes• Man-made: Gunshots
Using an air-gun to create seismic waves
A cross sectional map using info from seismic waves
Two types of Seismic waves used
• P-waves
Primary-pressure wave (longitudinal)
Fastest wave
Some of the wave goes through all
material, some reflects back
Changes direction at each boundary
S-waves
• Secondary, shear
• Slower than P-waves
• Can not go through liquid
Info from Seismic waves
• Can tell the texture of the rock through interpretation of the speed of seismic waves
• Seismic waves move faster in more dense material
• The s-waves can not travel thru any liquid
Seismic wave speed
• Faster in lithosphere than crust
• Slows down in Asthenosphere
• Increases through the rest of the mantle
• Drops off in Outer CoreNo S waves
Shadow Zone
Magnetosphere
• The range of Earth’s magnetic field
• Extends beyond the atmosphere into space
• Northern lights
• May be caused by the movement of the Earth’s liquid core
There may be another source of magnetic field
• Both Sun and Moon have magnetic fields
• Sun contains very little iron
• Moon does not have a liquid core
Northern Lights
• Aurora Borealis• Result from the interaction between the
-Solar wind (charged particles expelled from the outer edge of the sun)
-Earth’s magnetosphere
-Earth’s Atmosphere
Best seen in winter (less water vapor in air) at the poles
Fig. 12-26, pg. 356